Comparison of inter- and intra-chromosomal aberrations in blood samples exposed to different dose rates of gamma radiation.

Peripheral blood samples obtained from a normal healthy volunteer were exposed in vitro to gamma radiation with various doses at different dose rates of 1.0, 0.1 and 0.0014 Gy min(-1). The exposed samples were analysed for different chromosomal aberrations such as dicentrics (DC), centric rings (CR) and double-minutes (DM). The ratio of DC chromosomes (inter) to the total number of centric rings (CR) and double-minutes (DM) (CR + DM = intra) were analysed for all the three dose rates. The study showed that the frequency of inter-arm chromosomal aberrations was more then three times higher than that observed with intra-arm chromosomal aberrations in samples exposed at a dose rate of 1.0 and 0.1 Gy min (-1). However, the frequency of inter- and intra-arm chromosomal aberrations were almost same (ratio 1:1) in samples exposed at a dose rate of 0.0014 Gy min(-1). This paper discusses the usefulness of the ratio of inter- and intra-arm chromosome aberration in finding out whether the sample was exposed to high or low dose rate radiation.